1. Field of the Invention
The present invention generally relates to a playback apparatus, and more particularly to an apparatus for controlling a playback procedure according to playback description data.
2. Description of the Related Art
With recent digital video players, DVD (digital versatile or video disc) players, etc., digital motion pictures have become familiar to the general public. Also, advances in AV (audio visual) equipment and computer equipment have made it possible to edit motion pictures at home as well as at studios.
FIG. 15 illustrates the relationship of moving image data in a conventional so-called non-linear video editing system. In FIG. 15, moving image data A 1501 and moving image data B 1502 are raw material data which have not been edited, and moving image data C 1503 is newly-generated data which has been edited. In such a conventional non-linear editing system, raw material moving image data are, if necessary, decoded, cut in or cut out along the time axis, rearranged, or have various video effects applied thereto, such as, for example, a wipe between cuts, thereby achieving video rendering, or are re-encoded, if necessary, thereby creating new moving image data.
Conventional systems of this type have disadvantages. In such non-linear editing systems, additional effects, such as video effects, are combined into edited moving image data. Consequently, the additional effects cannot be segregated. Thus, the effect alone cannot be deleted at a later time, or the effect cannot be replaced with another effect. Moreover, even the raw-material image data cannot be identified from the image data having an effect applied thereto.
In another conventional technique, the playback sequence of moving image data or playback effects including video effects are dictated by playback description data which is described in a playback description language known as SMIL (Synchronized Multimedia Integration Language), and the described data is executed by a player, thereby editing a motion picture program without modifying the raw-material moving image data. FIG. 16 shows an example in which a transition effect, which is set between two moving images, is described in SMIL.
In playback description data, a video effect can be described as a playback effect, and can be modified or deleted. However, execution of a particular effect depends upon the playback apparatus. Depending upon the specification of the playback apparatus, a described effect may not be executed. Thus, it is not appropriate that the description of intelligent and complicated video effects and compatibility thereof be defined as the specification of description schemes.
For this reason, a method has been suggested which includes providing, separately from raw-material image data, a modified data object which has been rendered according to a specified effect or the like, and using playback description data to maintain the amount of shift for the cut-in and cut-out points that are shifted because of the addition of the modified data object, so that various effects including video effects can be added or deleted in a completely reversible way.
This method, however, is not without disadvantages. In this method, playback description data and data objects to be played are stored in different files. Consequently, it is possible to delete (erase) data objects or modified data objects necessary for the playback operation according to the playback description data. In particular, during many editing operations, while a file for the playback description data is left, a file for the modified data object specified in the playback description data may be erased unintentionally.
In this case, data cannot be played back according to the procedure specified in the playback description data.